The present invention relates to fluid infusion systems, and more particularly to an improved apparatus and method for accurately metering the flow rate of fluid through an administration set.
The infusion of fluids such as parenteral solutions and blood into the human body is usually accomplished by means of an administration set in conjunction with metering means for controlling the rate of fluid flow through the set. One form of metering means which is attractive for this application is the peristaltic-type pump, which operates to repeatedly and progressively compress and expand a section of tubing of the administration set so as to cause fluid to flow through the set at a controlled rate, thereby avoiding the need for direct contact with fluid and the attendant risk of contamination.
Because of its partial non-resiliency, tubing formed of vinyl and other thermal plastic materials commonly utilized in administration sets may permanently change its shape and size with time as a result of repeated stretch-compressive cycling, such as is inherent in the operation of a peristaltic-type pump, with the result that the rate at which fluid is delivered by the pump may undesirably vary with time. One means for minimizing the effects of stretch-compressive cycling for improved metering accuracy is described in U.S. Pat. No. 4,155,362, which issued to Thurman S. Jess on May 22, 1979, and is assigned to the present assignee. Basically this patent provides for flow restriction means downline of the peristaltic pump to obtain a downline fluid pressure at the point of compression by the pump which assists in restoring the tubing to its original shape following compression. This system has been successfully incorporated in the Model 2M8014 infusion pump manufactured by the Travenol Division of Baxter Travenol Laboratories, Inc., of Deerfield, Ill.
The present invention is directed to a peristaltic-type system and method for infusing fluids through vinyl tubing and the like which provides an additional improvement in metering accuracy by further minimizing physical dimensional variations in the tubing under repeated compression. Basically, this is accomplished by providing fluid pressurization means upline of the metering pump so that the fluid in the tubing segment upon which the metering pump is acting is pressurized both upline and downline of the point of engagement of the metering pump.
Accordingly, it is a general object of the present invention to provide a new and improved fluid infusion system.
It is a more specific object of the present invention to provide a new and improved system for infusing fluids into the human body with improved metering accuracy.
It is another object of the present invention to provide new and improved metering apparatus for controlling the flow of fluid through the compressible tubing of an administration set with improved metering accuracy.
It is another object of the present invention to provide a new and improved method for infusing fluid into the human body with greater metering accuracy.